A biopic of the Supreme Court justice Ruth Bader Ginsburg could hardly seem timelier, given the current headlines about President Donald J. Trump’s new nominee for the high court, Brett Kavanaugh, as well as the surprise box-office success of the recent documentary “RBG.” But based on the first trailer for “On the Basis of Sex,” fictionalization may prove stranger than truth in this case.

For two years, Natalie Portman was slated to play Justice Ginsburg, but dropped out in 2017, only to be replaced by Felicity Jones. Ms. Jones was born in Birmingham, England, and initial impressions indicate she may not have nailed Ms. Ginsberg’s distinctive Brooklyn accent.

ON THE BASIS OF SEX - Official Trailer [HD]CreditCreditVideo by Focus Features

“On the Basis of Sex” depicts a landmark case, also prominently featured in “RBG,” in which Ms. Ginsburg argued in favor of fathers’ rights before the Supreme Court and struck a major blow against gender discrimination. The film was directed by Mimi Leder (“Deep Impact”) from a script by the first-time screenwriter Daniel Stiepleman, a nephew of Marty Ginsburg, and the cast also includes Justin Theroux, Kathy Bates and Sam Waterston.

The audience can render its verdict when “On the Basis of Sex” is released Dec. 25.